public CIMColorRamp ColorRamp {get; set;}

{
  // Note: call within QueuedTask.Run()
  {
    var fields = pointCloudSceneLayer.GetAvailablePointCloudRendererFields(
                            PointCloudRendererType.StretchRenderer);
    var stretchDef = new PointCloudRendererDefinition(
                              PointCloudRendererType.StretchRenderer)
    {
      //Will be either ELEVATION or INTENSITY
      Field = fields[0]
    };
    //Create the CIM Renderer
    var stretchRenderer = pointCloudSceneLayer.CreateRenderer(stretchDef)
                                        as CIMPointCloudStretchRenderer;
    //Apply a color ramp
    var style = Project.Current.GetItems<StyleProjectItem>()
                                    .First(s => s.Name == "ArcGIS Colors");
    var colorRamp = style.SearchColorRamps("").First();
    stretchRenderer.ColorRamp = colorRamp.ColorRamp;
    //Apply modulation
    stretchRenderer.ColorModulation = new CIMColorModulationInfo()
    {
      MinValue = 0,
      MaxValue = 100
    };
    //apply the renderer
    pointCloudSceneLayer.SetRenderer(stretchRenderer);
  }
}